The objectives of this research are to investigate, using an isolated perfused lung preparation developed in our laboratory, the pulmonary metabolism and distribution of benzo(a)pyrene and to assess the effects of agents known to influence its carcinogenic potency. This research is attempting to clarify whether a change in metabolic pathway, rates or distribution in the tissues could account for differences in the carcinogenic effect. Control studies are nearing completion which include non-induced and i.p. B (a)P induced rabbits followed by intratracheal administered in vitro of C14-B(a)P suspensions or C14-B(a)P absorbed onto ferric oxide. Blood taken at various time intervals throughout the perfusion, and tissues, including pulmonary alveolar macrophages, trachea-bronchi, lavage fluid and the lung proper, are extracted. Concentrates are chromatographed (TLC and HPLC) and metabolites quantitated. The group receiving i.p. B(a)P pretreatment was found to have an increased metabolic rate of 8.5 times that of the control when comparing rates of appearance in the blood. The data on distribution are not available at this time. Tentative identifications of the metabolites include the 9,10-, 7,8- and 4,5- dihydrodiols, 3-hydroxy, 3,6-dione and conjugated metabolites. Current plans include intratracheal pretreatment in vivo of ferric oxide, B(a)P absorbed onto ferric oxide and B(a)P alone, followed by the in vitro experiments as mentioned previously.